Aren
/
NetBSD
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Fix spurious page faults by double word aligning the source and not the 

destination. Thank's to Ian Dall for this fix.
This commit is contained in:
matthias 1999-06-06 19:49:11 +00:00
parent 7cdfe2dbc5
commit bb36354c10
1 changed files with 11 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
lib/libc/arch/ns32k/string/strcpy.S
View File

@ -1,4 +1,4 @@
/* $NetBSD: strcpy.S,v 1.3 1998/04/03 22:58:10 matthias Exp $ */
/* $NetBSD: strcpy.S,v 1.4 1999/06/06 19:49:11 matthias Exp $ */
/*
* Written by Randy Hyde, 1993
@ -8,7 +8,7 @@
#include <machine/asm.h>
#if defined(LIBC_SCCS)
RCSID("$NetBSD: strcpy.S,v 1.3 1998/04/03 22:58:10 matthias Exp $")
RCSID("$NetBSD: strcpy.S,v 1.4 1999/06/06 19:49:11 matthias Exp $")
#endif
/*
@ -23,16 +23,15 @@ KENTRY(strcpy, 8)
movd B_ARG0,r2
/*
* First begin by seeing if we can doubleword align the
* pointers. The following code only aligns the pointer in R2.
* If the L.O. two bits of R1 do not match, it's going to run
* slower but there is nothing we can do about that. Better to
* have at least one of them double word aligned rather than
* neither.
* We need to double word align the src (R1). When we read
* by double words we can read potentially up to 3 bytes
* past the null terminating byte. We can avoid spurious page
* faults by double word aligning the source. It also runs
* faster. IWD
*/
movqd 3,r3
andd r2,r3
andd r1,r3
0: casew 1f(pc)[r3:w]
1: .word 5f-0b
@ -61,13 +60,13 @@ KENTRY(strcpy, 8)
addqd 1,r2
/*
* Okay, when we get down here R2 points at a double word
* aligned destination block of bytes, R1 points at another
* Okay, when we get down here R1 points at a double word
* aligned source block of bytes, R2 points at the destination
* block of bytes (typically, though not always double word
* aligned).
* This guy processes four bytes at a time and checks for the
* zero terminating byte amongst the bytes in the double word.
* This algorithm is de to Dave Rand.
* This algorithm is due to Dave Rand.
*
* Sneaky test for zero amongst four bytes:
*